Persist text elements through TUI input and history (#9393)

Continuation of breaking up this PR
https://github.com/openai/codex/pull/9116

## Summary
- Thread user text element ranges through TUI/TUI2 input, submission,
queueing, and history so placeholders survive resume/edit flows.
- Preserve local image attachments alongside text elements and rehydrate
placeholders when restoring drafts.
- Keep model-facing content shapes clean by attaching UI metadata only
to user input/events (no API content changes).

## Key Changes
- TUI/TUI2 composer now captures text element ranges, trims them with
text edits, and restores them when submission is suppressed.
- User history cells render styled spans for text elements and keep
local image paths for future rehydration.
- Initial chat widget bootstraps accept empty `initial_text_elements` to
keep initialization uniform.
- Protocol/core helpers updated to tolerate the new InputText field
shape without changing payloads sent to the API.

codex-rs/core/src/agent/control.rs

@@ -58,7 +58,7 @@ impl AgentControl {
                 Op::UserInput {
                     items: vec![UserInput::Text {
                         text: prompt,
-                        // Plain text conversion has no UI element ranges.
+                        // Agent control prompts are plain text with no UI text elements.
                         text_elements: Vec::new(),
                     }],
                     final_output_json_schema: None,

codex-rs/core/src/codex.rs

@@ -2485,6 +2485,7 @@ mod handlers {
             Arc::clone(&turn_context),
             vec![UserInput::Text {
                 text: turn_context.compact_prompt().to_string(),
+                // Compaction prompt is synthesized; no UI element ranges to preserve.
                 text_elements: Vec::new(),
             }],
             CompactTask,
@@ -2694,6 +2695,7 @@ async fn spawn_review_thread(
     // Seed the child task with the review prompt as the initial user message.
     let input: Vec<UserInput> = vec![UserInput::Text {
         text: review_prompt,
+        // Review prompt is synthesized; no UI element ranges to preserve.
         text_elements: Vec::new(),
     }];
     let tc = Arc::new(review_turn_context);

codex-rs/core/src/compact.rs

@@ -46,7 +46,7 @@ pub(crate) async fn run_inline_auto_compact_task(
     let prompt = turn_context.compact_prompt().to_string();
     let input = vec![UserInput::Text {
         text: prompt,
-        // Plain text conversion has no UI element ranges.
+        // Compaction prompt is synthesized; no UI element ranges to preserve.
         text_elements: Vec::new(),
     }];
 

codex-rs/core/src/event_mapping.rs

@@ -52,7 +52,7 @@ fn parse_user_message(message: &[ContentItem]) -> Option<UserMessageItem> {
                 }
                 content.push(UserInput::Text {
                     text: text.clone(),
-                    // Plain text conversion has no UI element ranges.
+                    // Model input content does not carry UI element ranges.
                     text_elements: Vec::new(),
                 });
             }